She waited on tables as usual that day, her twentieth birthday. She always worked on Fridays, but if things had gone according to plan that particular Friday, she would have had the night off. The other part-time girl had agreed to switch shifts with her as a matter of course: being screamed at by an angry chef while lugging pumpkin gnocchi and seafood fritto to customers’ tables was not a normal way to spend one’s twentieth birthday. But the other girl had aggravated a cold and gone to bed with unstoppable diarrhea and a fever of 104, so she…